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base_transformer

This submodule implements the BaseTransformer and Quantity classes for turning filters parsed by lark into backend-specific queries.

__all__ = ('BaseTransformer', 'Quantity') module-attribute

BadRequest

Bases: OptimadeHTTPException

400 Bad Request

Source code in optimade/exceptions.py 
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class BadRequest(OptimadeHTTPException):
    """400 Bad Request"""

    status_code: int = 400
    title: str = "Bad Request"

BaseResourceMapper

Generic Resource Mapper that defines and performs the mapping between objects in the database and the resource objects defined by the specification.

Attributes:

Name Type Description
ALIASES tuple[tuple[str, str], ...]

a tuple of aliases between OPTIMADE field names and the field names in the database , e.g. (("elements", "custom_elements_field")).
LENGTH_ALIASES tuple[tuple[str, str], ...]

a tuple of aliases between a field name and another field that defines its length, to be used when querying, e.g. (("elements", "nelements")). e.g. (("elements", "custom_elements_field")).
ENTRY_RESOURCE_CLASS type[EntryResource]

The entry type that this mapper corresponds to.
PROVIDER_FIELDS tuple[str, ...]

a tuple of extra field names that this mapper should support when querying with the database prefix.
TOP_LEVEL_NON_ATTRIBUTES_FIELDS set[str]

the set of top-level field names common to all endpoints.
SUPPORTED_PREFIXES set[str]

The set of prefixes registered by this mapper.
ALL_ATTRIBUTES set[str]

The set of attributes defined across the entry resource class and the server configuration.
ENTRY_RESOURCE_ATTRIBUTES dict[str, Any]

A dictionary of attributes and their definitions defined by the schema of the entry resource class.
ENDPOINT str

The expected endpoint name for this resource, as defined by the type in the schema of the entry resource class.
Source code in optimade/server/mappers/entries.py 
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class BaseResourceMapper:
    """Generic Resource Mapper that defines and performs the mapping
    between objects in the database and the resource objects defined by
    the specification.

    Attributes:
        ALIASES: a tuple of aliases between
            OPTIMADE field names and the field names in the database ,
            e.g. `(("elements", "custom_elements_field"))`.
        LENGTH_ALIASES: a tuple of aliases between
            a field name and another field that defines its length, to be used
            when querying, e.g. `(("elements", "nelements"))`.
            e.g. `(("elements", "custom_elements_field"))`.
        ENTRY_RESOURCE_CLASS: The entry type that this mapper corresponds to.
        PROVIDER_FIELDS: a tuple of extra field names that this
            mapper should support when querying with the database prefix.
        TOP_LEVEL_NON_ATTRIBUTES_FIELDS: the set of top-level
            field names common to all endpoints.
        SUPPORTED_PREFIXES: The set of prefixes registered by this mapper.
        ALL_ATTRIBUTES: The set of attributes defined across the entry
            resource class and the server configuration.
        ENTRY_RESOURCE_ATTRIBUTES: A dictionary of attributes and their definitions
            defined by the schema of the entry resource class.
        ENDPOINT: The expected endpoint name for this resource, as defined by
            the `type` in the schema of the entry resource class.

    """

    try:
        from optimade.server.data import providers as PROVIDERS  # type: ignore
    except (ImportError, ModuleNotFoundError):
        PROVIDERS = {}

    KNOWN_PROVIDER_PREFIXES: set[str] = {
        prov["id"] for prov in PROVIDERS.get("data", [])
    }
    ALIASES: tuple[tuple[str, str], ...] = ()
    LENGTH_ALIASES: tuple[tuple[str, str], ...] = ()
    PROVIDER_FIELDS: tuple[str, ...] = ()
    ENTRY_RESOURCE_CLASS: type[EntryResource] = EntryResource
    RELATIONSHIP_ENTRY_TYPES: set[str] = {"references", "structures"}
    TOP_LEVEL_NON_ATTRIBUTES_FIELDS: set[str] = {"id", "type", "relationships", "links"}

    @classmethod
    @lru_cache(maxsize=NUM_ENTRY_TYPES)
    def all_aliases(cls) -> Iterable[tuple[str, str]]:
        """Returns all of the associated aliases for this entry type,
        including those defined by the server config. The first member
        of each tuple is the OPTIMADE-compliant field name, the second
        is the backend-specific field name.

        Returns:
            A tuple of alias tuples.

        """
        from optimade.server.config import CONFIG

        return (
            tuple(
                (f"_{CONFIG.provider.prefix}_{field}", field)
                if not field.startswith("_")
                else (field, field)
                for field in CONFIG.provider_fields.get(cls.ENDPOINT, [])
                if isinstance(field, str)
            )
            + tuple(
                (f"_{CONFIG.provider.prefix}_{field['name']}", field["name"])
                if not field["name"].startswith("_")
                else (field["name"], field["name"])
                for field in CONFIG.provider_fields.get(cls.ENDPOINT, [])
                if isinstance(field, dict)
            )
            + tuple(
                (f"_{CONFIG.provider.prefix}_{field}", field)
                if not field.startswith("_")
                else (field, field)
                for field in cls.PROVIDER_FIELDS
            )
            + tuple(CONFIG.aliases.get(cls.ENDPOINT, {}).items())
            + cls.ALIASES
        )

    @classproperty
    @lru_cache(maxsize=1)
    def SUPPORTED_PREFIXES(cls) -> set[str]:
        """A set of prefixes handled by this entry type.

        !!! note
            This implementation only includes the provider prefix,
            but in the future this property may be extended to include other
            namespaces (for serving fields from, e.g., other providers or
            domain-specific terms).

        """
        from optimade.server.config import CONFIG

        return {CONFIG.provider.prefix}

    @classproperty
    def ALL_ATTRIBUTES(cls) -> set[str]:
        """Returns all attributes served by this entry."""
        from optimade.server.config import CONFIG

        return (
            set(cls.ENTRY_RESOURCE_ATTRIBUTES)
            .union(
                cls.get_optimade_field(field)
                for field in CONFIG.provider_fields.get(cls.ENDPOINT, ())
                if isinstance(field, str)
            )
            .union(
                cls.get_optimade_field(field["name"])
                for field in CONFIG.provider_fields.get(cls.ENDPOINT, ())
                if isinstance(field, dict)
            )
            .union({cls.get_optimade_field(field) for field in cls.PROVIDER_FIELDS})
        )

    @classproperty
    def ENTRY_RESOURCE_ATTRIBUTES(cls) -> dict[str, Any]:
        """Returns the dictionary of attributes defined by the underlying entry resource class."""
        from optimade.server.schemas import retrieve_queryable_properties

        return retrieve_queryable_properties(cls.ENTRY_RESOURCE_CLASS)

    @classproperty
    @lru_cache(maxsize=NUM_ENTRY_TYPES)
    def ENDPOINT(cls) -> str:
        """Returns the expected endpoint for this mapper, corresponding
        to the `type` property of the resource class.

        """
        endpoint = cls.ENTRY_RESOURCE_CLASS.model_fields["type"].default
        if not endpoint and not isinstance(endpoint, str):
            raise ValueError("Type not set for this entry type!")
        return endpoint

    @classmethod
    @lru_cache(maxsize=NUM_ENTRY_TYPES)
    def all_length_aliases(cls) -> tuple[tuple[str, str], ...]:
        """Returns all of the associated length aliases for this class,
        including those defined by the server config.

        Returns:
            A tuple of length alias tuples.

        """
        from optimade.server.config import CONFIG

        return cls.LENGTH_ALIASES + tuple(
            CONFIG.length_aliases.get(cls.ENDPOINT, {}).items()
        )

    @classmethod
    @lru_cache(maxsize=128)
    def length_alias_for(cls, field: str) -> Optional[str]:
        """Returns the length alias for the particular field,
        or `None` if no such alias is found.

        Parameters:
            field: OPTIMADE field name.

        Returns:
            Aliased field as found in [`all_length_aliases()`][optimade.server.mappers.entries.BaseResourceMapper.all_length_aliases].

        """
        return dict(cls.all_length_aliases()).get(field, None)

    @classmethod
    @lru_cache(maxsize=128)
    def get_backend_field(cls, optimade_field: str) -> str:
        """Return the field name configured for the particular
        underlying database for the passed OPTIMADE field name, that would
        be used in an API filter.

        Aliases are read from
        [`all_aliases()`][optimade.server.mappers.entries.BaseResourceMapper.all_aliases].

        If a dot-separated OPTIMADE field is provided, e.g., `species.mass`, only the first part will be mapped.
        This means for an (OPTIMADE, DB) alias of (`species`, `kinds`), `get_backend_fields("species.mass")`
        will return `kinds.mass`.

        Arguments:
            optimade_field: The OPTIMADE field to attempt to map to the backend-specific field.

        Examples:
            >>> get_backend_field("chemical_formula_anonymous")
            'formula_anon'
            >>> get_backend_field("formula_anon")
            'formula_anon'
            >>> get_backend_field("_exmpl_custom_provider_field")
            'custom_provider_field'

        Returns:
            The mapped field name to be used in the query to the backend.

        """
        split = optimade_field.split(".")
        alias = dict(cls.all_aliases()).get(split[0], None)
        if alias is not None:
            return alias + ("." + ".".join(split[1:]) if len(split) > 1 else "")
        return optimade_field

    @classmethod
    @lru_cache(maxsize=128)
    def alias_for(cls, field: str) -> str:
        """Return aliased field name.

        !!! warning "Deprecated"
            This method is deprecated could be removed without further warning. Please use
            [`get_backend_field()`][optimade.server.mappers.entries.BaseResourceMapper.get_backend_field].

        Parameters:
            field: OPTIMADE field name.

        Returns:
            Aliased field as found in [`all_aliases()`][optimade.server.mappers.entries.BaseResourceMapper.all_aliases].

        """
        warnings.warn(
            "The `.alias_for(...)` method is deprecated, please use `.get_backend_field(...)`.",
            DeprecationWarning,
        )
        return cls.get_backend_field(field)

    @classmethod
    @lru_cache(maxsize=128)
    def get_optimade_field(cls, backend_field: str) -> str:
        """Return the corresponding OPTIMADE field name for the underlying database field,
        ready to be used to construct the OPTIMADE-compliant JSON response.

        Aliases are read from
        [`all_aliases()`][optimade.server.mappers.entries.BaseResourceMapper.all_aliases].

        Arguments:
            backend_field: The backend field to attempt to map to an OPTIMADE field.

        Examples:
            >>> get_optimade_field("chemical_formula_anonymous")
            'chemical_formula_anonymous'
            >>> get_optimade_field("formula_anon")
            'chemical_formula_anonymous'
            >>> get_optimade_field("custom_provider_field")
            '_exmpl_custom_provider_field'

        Returns:
            The mapped field name to be used in an OPTIMADE-compliant response.

        """
        return {alias: real for real, alias in cls.all_aliases()}.get(
            backend_field, backend_field
        )

    @classmethod
    @lru_cache(maxsize=128)
    def alias_of(cls, field: str) -> str:
        """Return de-aliased field name, if it exists,
        otherwise return the input field name.

        !!! warning "Deprecated"
            This method is deprecated could be removed without further warning. Please use
            [`get_optimade_field()`][optimade.server.mappers.entries.BaseResourceMapper.get_optimade_field].

        Parameters:
            field: Field name to be de-aliased.

        Returns:
            De-aliased field name, falling back to returning `field`.

        """
        warnings.warn(
            "The `.alias_of(...)` method is deprecated, please use `.get_optimade_field(...)`.",
            DeprecationWarning,
        )
        return cls.get_optimade_field(field)

    @classmethod
    @lru_cache(maxsize=NUM_ENTRY_TYPES)
    def get_required_fields(cls) -> set:
        """Get REQUIRED response fields.

        Returns:
            REQUIRED response fields.

        """
        return cls.TOP_LEVEL_NON_ATTRIBUTES_FIELDS

    @classmethod
    def map_back(cls, doc: dict) -> dict:
        """Map properties from MongoDB to OPTIMADE.

        Starting from a MongoDB document `doc`, map the DB fields to the corresponding OPTIMADE fields.
        Then, the fields are all added to the top-level field "attributes",
        with the exception of other top-level fields, defined in `cls.TOP_LEVEL_NON_ATTRIBUTES_FIELDS`.
        All fields not in `cls.TOP_LEVEL_NON_ATTRIBUTES_FIELDS` + "attributes" will be removed.
        Finally, the `type` is given the value of the specified `cls.ENDPOINT`.

        Parameters:
            doc: A resource object in MongoDB format.

        Returns:
            A resource object in OPTIMADE format.

        """
        mapping = ((real, alias) for alias, real in cls.all_aliases())
        newdoc = {}
        reals = {real for _, real in cls.all_aliases()}
        for key in doc:
            if key not in reals:
                newdoc[key] = doc[key]
        for real, alias in mapping:
            if real in doc:
                newdoc[alias] = doc[real]

        if "attributes" in newdoc:
            raise Exception("Will overwrite doc field!")
        attributes = newdoc.copy()

        for field in cls.TOP_LEVEL_NON_ATTRIBUTES_FIELDS:
            value = attributes.pop(field, None)
            if value is not None:
                newdoc[field] = value
        for field in list(newdoc.keys()):
            if field not in cls.TOP_LEVEL_NON_ATTRIBUTES_FIELDS:
                del newdoc[field]

        newdoc["type"] = cls.ENDPOINT
        newdoc["attributes"] = attributes

        return newdoc

    @classmethod
    def deserialize(
        cls, results: Union[dict, Iterable[dict]]
    ) -> Union[list[EntryResource], EntryResource]:
        """Converts the raw database entries for this class into serialized models,
        mapping the data along the way.

        """
        if isinstance(results, dict):
            return cls.ENTRY_RESOURCE_CLASS(**cls.map_back(results))

        return [cls.ENTRY_RESOURCE_CLASS(**cls.map_back(doc)) for doc in results]

ALL_ATTRIBUTES()

Returns all attributes served by this entry.

Source code in optimade/server/mappers/entries.py 
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@classproperty
def ALL_ATTRIBUTES(cls) -> set[str]:
    """Returns all attributes served by this entry."""
    from optimade.server.config import CONFIG

    return (
        set(cls.ENTRY_RESOURCE_ATTRIBUTES)
        .union(
            cls.get_optimade_field(field)
            for field in CONFIG.provider_fields.get(cls.ENDPOINT, ())
            if isinstance(field, str)
        )
        .union(
            cls.get_optimade_field(field["name"])
            for field in CONFIG.provider_fields.get(cls.ENDPOINT, ())
            if isinstance(field, dict)
        )
        .union({cls.get_optimade_field(field) for field in cls.PROVIDER_FIELDS})
    )

ENDPOINT() cached

Returns the expected endpoint for this mapper, corresponding to the type property of the resource class.

Source code in optimade/server/mappers/entries.py 
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@classproperty
@lru_cache(maxsize=NUM_ENTRY_TYPES)
def ENDPOINT(cls) -> str:
    """Returns the expected endpoint for this mapper, corresponding
    to the `type` property of the resource class.

    """
    endpoint = cls.ENTRY_RESOURCE_CLASS.model_fields["type"].default
    if not endpoint and not isinstance(endpoint, str):
        raise ValueError("Type not set for this entry type!")
    return endpoint

ENTRY_RESOURCE_ATTRIBUTES()

Returns the dictionary of attributes defined by the underlying entry resource class.

Source code in optimade/server/mappers/entries.py 
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@classproperty
def ENTRY_RESOURCE_ATTRIBUTES(cls) -> dict[str, Any]:
    """Returns the dictionary of attributes defined by the underlying entry resource class."""
    from optimade.server.schemas import retrieve_queryable_properties

    return retrieve_queryable_properties(cls.ENTRY_RESOURCE_CLASS)

SUPPORTED_PREFIXES() cached

A set of prefixes handled by this entry type.

Note

This implementation only includes the provider prefix, but in the future this property may be extended to include other namespaces (for serving fields from, e.g., other providers or domain-specific terms).

Source code in optimade/server/mappers/entries.py 
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@classproperty
@lru_cache(maxsize=1)
def SUPPORTED_PREFIXES(cls) -> set[str]:
    """A set of prefixes handled by this entry type.

    !!! note
        This implementation only includes the provider prefix,
        but in the future this property may be extended to include other
        namespaces (for serving fields from, e.g., other providers or
        domain-specific terms).

    """
    from optimade.server.config import CONFIG

    return {CONFIG.provider.prefix}

alias_for(field) cached classmethod

Return aliased field name.

Deprecated

This method is deprecated could be removed without further warning. Please use get_backend_field().

Parameters:

Name Type Description Default
field str

OPTIMADE field name.

 required

Returns:

Type Description
str

Aliased field as found in all_aliases().
Source code in optimade/server/mappers/entries.py 
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@classmethod
@lru_cache(maxsize=128)
def alias_for(cls, field: str) -> str:
    """Return aliased field name.

    !!! warning "Deprecated"
        This method is deprecated could be removed without further warning. Please use
        [`get_backend_field()`][optimade.server.mappers.entries.BaseResourceMapper.get_backend_field].

    Parameters:
        field: OPTIMADE field name.

    Returns:
        Aliased field as found in [`all_aliases()`][optimade.server.mappers.entries.BaseResourceMapper.all_aliases].

    """
    warnings.warn(
        "The `.alias_for(...)` method is deprecated, please use `.get_backend_field(...)`.",
        DeprecationWarning,
    )
    return cls.get_backend_field(field)

alias_of(field) cached classmethod

Return de-aliased field name, if it exists, otherwise return the input field name.

Deprecated

This method is deprecated could be removed without further warning. Please use get_optimade_field().

Parameters:

Name Type Description Default
field str

Field name to be de-aliased.

 required

Returns:

Type Description
str

De-aliased field name, falling back to returning field.
Source code in optimade/server/mappers/entries.py 
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@classmethod
@lru_cache(maxsize=128)
def alias_of(cls, field: str) -> str:
    """Return de-aliased field name, if it exists,
    otherwise return the input field name.

    !!! warning "Deprecated"
        This method is deprecated could be removed without further warning. Please use
        [`get_optimade_field()`][optimade.server.mappers.entries.BaseResourceMapper.get_optimade_field].

    Parameters:
        field: Field name to be de-aliased.

    Returns:
        De-aliased field name, falling back to returning `field`.

    """
    warnings.warn(
        "The `.alias_of(...)` method is deprecated, please use `.get_optimade_field(...)`.",
        DeprecationWarning,
    )
    return cls.get_optimade_field(field)

all_aliases() cached classmethod

Returns all of the associated aliases for this entry type, including those defined by the server config. The first member of each tuple is the OPTIMADE-compliant field name, the second is the backend-specific field name.

Returns:

Type Description
Iterable[tuple[str, str]]

A tuple of alias tuples.
Source code in optimade/server/mappers/entries.py 
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@classmethod
@lru_cache(maxsize=NUM_ENTRY_TYPES)
def all_aliases(cls) -> Iterable[tuple[str, str]]:
    """Returns all of the associated aliases for this entry type,
    including those defined by the server config. The first member
    of each tuple is the OPTIMADE-compliant field name, the second
    is the backend-specific field name.

    Returns:
        A tuple of alias tuples.

    """
    from optimade.server.config import CONFIG

    return (
        tuple(
            (f"_{CONFIG.provider.prefix}_{field}", field)
            if not field.startswith("_")
            else (field, field)
            for field in CONFIG.provider_fields.get(cls.ENDPOINT, [])
            if isinstance(field, str)
        )
        + tuple(
            (f"_{CONFIG.provider.prefix}_{field['name']}", field["name"])
            if not field["name"].startswith("_")
            else (field["name"], field["name"])
            for field in CONFIG.provider_fields.get(cls.ENDPOINT, [])
            if isinstance(field, dict)
        )
        + tuple(
            (f"_{CONFIG.provider.prefix}_{field}", field)
            if not field.startswith("_")
            else (field, field)
            for field in cls.PROVIDER_FIELDS
        )
        + tuple(CONFIG.aliases.get(cls.ENDPOINT, {}).items())
        + cls.ALIASES
    )

all_length_aliases() cached classmethod

Returns all of the associated length aliases for this class, including those defined by the server config.

Returns:

Type Description
tuple[tuple[str, str], ...]

A tuple of length alias tuples.
Source code in optimade/server/mappers/entries.py 
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@classmethod
@lru_cache(maxsize=NUM_ENTRY_TYPES)
def all_length_aliases(cls) -> tuple[tuple[str, str], ...]:
    """Returns all of the associated length aliases for this class,
    including those defined by the server config.

    Returns:
        A tuple of length alias tuples.

    """
    from optimade.server.config import CONFIG

    return cls.LENGTH_ALIASES + tuple(
        CONFIG.length_aliases.get(cls.ENDPOINT, {}).items()
    )

deserialize(results) classmethod

Converts the raw database entries for this class into serialized models, mapping the data along the way.

Source code in optimade/server/mappers/entries.py 
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@classmethod
def deserialize(
    cls, results: Union[dict, Iterable[dict]]
) -> Union[list[EntryResource], EntryResource]:
    """Converts the raw database entries for this class into serialized models,
    mapping the data along the way.

    """
    if isinstance(results, dict):
        return cls.ENTRY_RESOURCE_CLASS(**cls.map_back(results))

    return [cls.ENTRY_RESOURCE_CLASS(**cls.map_back(doc)) for doc in results]

get_backend_field(optimade_field) cached classmethod

Return the field name configured for the particular underlying database for the passed OPTIMADE field name, that would be used in an API filter.

Aliases are read from all_aliases().

If a dot-separated OPTIMADE field is provided, e.g., species.mass, only the first part will be mapped. This means for an (OPTIMADE, DB) alias of (species, kinds), get_backend_fields("species.mass") will return kinds.mass.

Parameters:

Name Type Description Default
optimade_field str

The OPTIMADE field to attempt to map to the backend-specific field.

 required

Examples:

>>> get_backend_field("chemical_formula_anonymous")
'formula_anon'
>>> get_backend_field("formula_anon")
'formula_anon'
>>> get_backend_field("_exmpl_custom_provider_field")
'custom_provider_field'

Returns:

Type Description
str

The mapped field name to be used in the query to the backend.
Source code in optimade/server/mappers/entries.py 
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@classmethod
@lru_cache(maxsize=128)
def get_backend_field(cls, optimade_field: str) -> str:
    """Return the field name configured for the particular
    underlying database for the passed OPTIMADE field name, that would
    be used in an API filter.

    Aliases are read from
    [`all_aliases()`][optimade.server.mappers.entries.BaseResourceMapper.all_aliases].

    If a dot-separated OPTIMADE field is provided, e.g., `species.mass`, only the first part will be mapped.
    This means for an (OPTIMADE, DB) alias of (`species`, `kinds`), `get_backend_fields("species.mass")`
    will return `kinds.mass`.

    Arguments:
        optimade_field: The OPTIMADE field to attempt to map to the backend-specific field.

    Examples:
        >>> get_backend_field("chemical_formula_anonymous")
        'formula_anon'
        >>> get_backend_field("formula_anon")
        'formula_anon'
        >>> get_backend_field("_exmpl_custom_provider_field")
        'custom_provider_field'

    Returns:
        The mapped field name to be used in the query to the backend.

    """
    split = optimade_field.split(".")
    alias = dict(cls.all_aliases()).get(split[0], None)
    if alias is not None:
        return alias + ("." + ".".join(split[1:]) if len(split) > 1 else "")
    return optimade_field

get_optimade_field(backend_field) cached classmethod

Return the corresponding OPTIMADE field name for the underlying database field, ready to be used to construct the OPTIMADE-compliant JSON response.

Aliases are read from all_aliases().

Parameters:

Name Type Description Default
backend_field str

The backend field to attempt to map to an OPTIMADE field.

 required

Examples:

>>> get_optimade_field("chemical_formula_anonymous")
'chemical_formula_anonymous'
>>> get_optimade_field("formula_anon")
'chemical_formula_anonymous'
>>> get_optimade_field("custom_provider_field")
'_exmpl_custom_provider_field'

Returns:

Type Description
str

The mapped field name to be used in an OPTIMADE-compliant response.
Source code in optimade/server/mappers/entries.py 
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@classmethod
@lru_cache(maxsize=128)
def get_optimade_field(cls, backend_field: str) -> str:
    """Return the corresponding OPTIMADE field name for the underlying database field,
    ready to be used to construct the OPTIMADE-compliant JSON response.

    Aliases are read from
    [`all_aliases()`][optimade.server.mappers.entries.BaseResourceMapper.all_aliases].

    Arguments:
        backend_field: The backend field to attempt to map to an OPTIMADE field.

    Examples:
        >>> get_optimade_field("chemical_formula_anonymous")
        'chemical_formula_anonymous'
        >>> get_optimade_field("formula_anon")
        'chemical_formula_anonymous'
        >>> get_optimade_field("custom_provider_field")
        '_exmpl_custom_provider_field'

    Returns:
        The mapped field name to be used in an OPTIMADE-compliant response.

    """
    return {alias: real for real, alias in cls.all_aliases()}.get(
        backend_field, backend_field
    )

get_required_fields() cached classmethod

Get REQUIRED response fields.

Returns:

Type Description
set

REQUIRED response fields.
Source code in optimade/server/mappers/entries.py 
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@classmethod
@lru_cache(maxsize=NUM_ENTRY_TYPES)
def get_required_fields(cls) -> set:
    """Get REQUIRED response fields.

    Returns:
        REQUIRED response fields.

    """
    return cls.TOP_LEVEL_NON_ATTRIBUTES_FIELDS

length_alias_for(field) cached classmethod

Returns the length alias for the particular field, or None if no such alias is found.

Parameters:

Name Type Description Default
field str

OPTIMADE field name.

 required

Returns:

Type Description
Optional[str]

Aliased field as found in all_length_aliases().
Source code in optimade/server/mappers/entries.py 
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@classmethod
@lru_cache(maxsize=128)
def length_alias_for(cls, field: str) -> Optional[str]:
    """Returns the length alias for the particular field,
    or `None` if no such alias is found.

    Parameters:
        field: OPTIMADE field name.

    Returns:
        Aliased field as found in [`all_length_aliases()`][optimade.server.mappers.entries.BaseResourceMapper.all_length_aliases].

    """
    return dict(cls.all_length_aliases()).get(field, None)

map_back(doc) classmethod

Map properties from MongoDB to OPTIMADE.

Starting from a MongoDB document doc, map the DB fields to the corresponding OPTIMADE fields. Then, the fields are all added to the top-level field "attributes", with the exception of other top-level fields, defined in cls.TOP_LEVEL_NON_ATTRIBUTES_FIELDS. All fields not in cls.TOP_LEVEL_NON_ATTRIBUTES_FIELDS + "attributes" will be removed. Finally, the type is given the value of the specified cls.ENDPOINT.

Parameters:

Name Type Description Default
doc dict

A resource object in MongoDB format.

 required

Returns:

Type Description
dict

A resource object in OPTIMADE format.
Source code in optimade/server/mappers/entries.py 
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@classmethod
def map_back(cls, doc: dict) -> dict:
    """Map properties from MongoDB to OPTIMADE.

    Starting from a MongoDB document `doc`, map the DB fields to the corresponding OPTIMADE fields.
    Then, the fields are all added to the top-level field "attributes",
    with the exception of other top-level fields, defined in `cls.TOP_LEVEL_NON_ATTRIBUTES_FIELDS`.
    All fields not in `cls.TOP_LEVEL_NON_ATTRIBUTES_FIELDS` + "attributes" will be removed.
    Finally, the `type` is given the value of the specified `cls.ENDPOINT`.

    Parameters:
        doc: A resource object in MongoDB format.

    Returns:
        A resource object in OPTIMADE format.

    """
    mapping = ((real, alias) for alias, real in cls.all_aliases())
    newdoc = {}
    reals = {real for _, real in cls.all_aliases()}
    for key in doc:
        if key not in reals:
            newdoc[key] = doc[key]
    for real, alias in mapping:
        if real in doc:
            newdoc[alias] = doc[real]

    if "attributes" in newdoc:
        raise Exception("Will overwrite doc field!")
    attributes = newdoc.copy()

    for field in cls.TOP_LEVEL_NON_ATTRIBUTES_FIELDS:
        value = attributes.pop(field, None)
        if value is not None:
            newdoc[field] = value
    for field in list(newdoc.keys()):
        if field not in cls.TOP_LEVEL_NON_ATTRIBUTES_FIELDS:
            del newdoc[field]

    newdoc["type"] = cls.ENDPOINT
    newdoc["attributes"] = attributes

    return newdoc

BaseTransformer

Bases: Transformer, ABC

Generic filter transformer that handles various parts of the grammar in a backend non-specific way.

Attributes:

Name Type Description
operator_map dict[str, Optional[str]]

A map from comparison operators to their backend-specific versions.
mapper Optional[type[BaseResourceMapper]]

A resource mapper object that defines the expected fields and acts as a container for various field-related configuration.
Source code in optimade/filtertransformers/base_transformer.py 
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class BaseTransformer(Transformer, abc.ABC):
    """Generic filter transformer that handles various
    parts of the grammar in a backend non-specific way.

    Attributes:
        operator_map: A map from comparison operators
            to their backend-specific versions.
        mapper: A resource mapper object that defines the
            expected fields and acts as a container for
            various field-related configuration.

    """

    mapper: Optional[type[BaseResourceMapper]] = None
    operator_map: dict[str, Optional[str]] = {
        "<": None,
        "<=": None,
        ">": None,
        ">=": None,
        "!=": None,
        "=": None,
    }

    # map from operators to their syntactic (as opposed to logical) inverse to handle
    # equivalence between cases like "A > 3" and "3 < A".
    _reversed_operator_map = {
        ">": "<",
        ">=": "<=",
        "<": ">",
        "<=": ">=",
        "=": "=",
        "!=": "!=",
    }

    _quantity_type: type[Quantity] = Quantity
    _quantities = None

    def __init__(
        self, mapper: Optional[type[BaseResourceMapper]] = None
    ):  # pylint: disable=super-init-not-called
        """Initialise the transformer object, optionally loading in a
        resource mapper for use when post-processing.

        """
        self.mapper = mapper

    @property
    def backend_mapping(self) -> dict[str, Quantity]:
        """A mapping between backend field names (aliases) and the corresponding
        [`Quantity`][optimade.filtertransformers.base_transformer.Quantity] object.
        """
        return {
            quantity.backend_field: quantity for _, quantity in self.quantities.items()  # type: ignore[misc]
        }

    @property
    def quantities(self) -> dict[str, Quantity]:
        """A mapping from the OPTIMADE field name to the corresponding
        [`Quantity`][optimade.filtertransformers.base_transformer.Quantity] objects.
        """
        if self._quantities is None:
            self._quantities = self._build_quantities()

        return self._quantities

    @quantities.setter
    def quantities(self, quantities: dict[str, Quantity]) -> None:
        self._quantities = quantities

    def _build_quantities(self) -> dict[str, Quantity]:
        """Creates a dictionary of field names mapped to
        [`Quantity`][optimade.filtertransformers.base_transformer.Quantity] objects from the
        fields registered by the mapper.

        """

        quantities = {}

        if self.mapper is not None:
            for field in self.mapper.ALL_ATTRIBUTES:
                alias = self.mapper.get_backend_field(field)
                # Allow length aliases to be defined relative to either backend fields or OPTIMADE fields,
                # with preference for those defined from OPTIMADE fields
                length_alias = self.mapper.length_alias_for(
                    field
                ) or self.mapper.length_alias_for(alias)

                if field not in quantities:
                    quantities[field] = self._quantity_type(
                        name=field, backend_field=alias
                    )

                if length_alias:
                    if length_alias not in quantities:
                        quantities[length_alias] = self._quantity_type(
                            name=length_alias,
                            backend_field=self.mapper.get_backend_field(length_alias),
                        )
                    quantities[field].length_quantity = quantities[length_alias]

        return quantities

    def postprocess(self, query) -> Any:
        """Post-process the query according to the rules defined for
        the backend, returning the backend-specific query.

        """
        return query

    def transform(self, tree: Tree) -> Any:
        """Transform the query using the Lark `Transformer` then run the
        backend-specific post-processing methods.

        """
        return self.postprocess(super().transform(tree))

    def __default__(self, data, children, meta):
        """The default rule to call when no definition is found for a particular construct."""
        raise NotImplementedError(
            f"Calling __default__, i.e., unknown grammar concept. data: {data}, children: {children}, meta: {meta}"
        )

    def filter(self, arg):
        """filter: expression*"""
        return arg[0] if arg else None

    @v_args(inline=True)
    def constant(self, value):
        """constant: string | number"""
        # Note: Return as is.
        return value

    @v_args(inline=True)
    def value(self, value):
        """value: string | number | property"""
        # Note: Return as is.
        return value

    @v_args(inline=True)
    def non_string_value(self, value):
        """non_string_value: number | property"""
        # Note: Return as is.
        return value

    @v_args(inline=True)
    def not_implemented_string(self, value):
        """not_implemented_string: value

        Raises:
            NotImplementedError: For further information, see Materials-Consortia/OPTIMADE issue 157:
                https://github.com/Materials-Consortia/OPTIMADE/issues/157

        """
        raise NotImplementedError("Comparing strings is not yet implemented.")

    def property(self, args: list) -> Any:
        """property: IDENTIFIER ( "." IDENTIFIER )*

        If this transformer has an associated mapper, the property
        will be compared to possible relationship entry types and
        for any supported provider prefixes. If there is a match,
        this rule will return a string and not a dereferenced
        [`Quantity`][optimade.filtertransformers.base_transformer.Quantity].

        Raises:
            BadRequest: If the property does not match any
                of the above rules.

        """
        quantity_name = str(args[0])

        # If the quantity name matches an entry type (indicating a relationship filter)
        # then simply return the quantity name; the inherited property
        # must then handle any further nested identifiers
        if self.mapper:
            if quantity_name in self.mapper.RELATIONSHIP_ENTRY_TYPES:
                return quantity_name

        if self.quantities and quantity_name not in self.quantities:
            # If the quantity is provider-specific, but does not match this provider,
            # then return the quantity name such that it can be treated as unknown.
            # If the prefix does not match another known provider, also emit a warning
            # If the prefix does match a known provider, do not return a warning.
            # Following [Handling unknown property names](https://github.com/Materials-Consortia/OPTIMADE/blob/master/optimade.rst#handling-unknown-property-names)
            if self.mapper and quantity_name.startswith("_"):
                prefix = quantity_name.split("_")[1]
                if prefix not in self.mapper.SUPPORTED_PREFIXES:
                    if prefix not in self.mapper.KNOWN_PROVIDER_PREFIXES:
                        warnings.warn(
                            UnknownProviderProperty(
                                f"Field {quantity_name!r} has an unrecognised prefix: this property has been treated as UNKNOWN."
                            )
                        )

                    return quantity_name

            raise BadRequest(
                detail=f"'{quantity_name}' is not a known or searchable quantity"
            )

        quantity = self.quantities.get(quantity_name, None)
        if quantity is None:
            quantity = self._quantity_type(name=str(quantity_name))

        return quantity

    @v_args(inline=True)
    def string(self, string):
        """string: ESCAPED_STRING"""
        return string.strip('"')

    @v_args(inline=True)
    def signed_int(self, number):
        """signed_int : SIGNED_INT"""
        return int(number)

    @v_args(inline=True)
    def number(self, number):
        """number: SIGNED_INT | SIGNED_FLOAT"""
        if TYPE_CHECKING:  # pragma: no cover
            type_: Union[type[int], type[float]]

        if number.type == "SIGNED_INT":
            type_ = int
        elif number.type == "SIGNED_FLOAT":
            type_ = float
        return type_(number)

    @v_args(inline=True)
    def comparison(self, value):
        """comparison: constant_first_comparison | property_first_comparison"""
        # Note: Return as is.
        return value

    def value_list(self, arg):
        """value_list: [ OPERATOR ] value ( "," [ OPERATOR ] value )*"""

    def value_zip(self, arg):
        """value_zip: [ OPERATOR ] value ":" [ OPERATOR ] value (":" [ OPERATOR ] value)*"""
        pass

    def value_zip_list(self, arg):
        """value_zip_list: value_zip ( "," value_zip )*"""

    def expression(self, arg):
        """expression: expression_clause ( OR expression_clause )"""

    def expression_clause(self, arg):
        """expression_clause: expression_phrase ( AND expression_phrase )*"""

    def expression_phrase(self, arg):
        """expression_phrase: [ NOT ] ( comparison | "(" expression ")" )"""

    def property_first_comparison(self, arg):
        """property_first_comparison:
        property ( value_op_rhs
                 | known_op_rhs
                 | fuzzy_string_op_rhs
                 | set_op_rhs
                 | set_zip_op_rhs
                 | length_op_rhs )

        """

    def constant_first_comparison(self, arg):
        """constant_first_comparison: constant OPERATOR ( non_string_value | not_implemented_string )"""

    @v_args(inline=True)
    def value_op_rhs(self, operator, value):
        """value_op_rhs: OPERATOR value"""

    def known_op_rhs(self, arg):
        """known_op_rhs: IS ( KNOWN | UNKNOWN )"""

    def fuzzy_string_op_rhs(self, arg):
        """fuzzy_string_op_rhs: CONTAINS value | STARTS [ WITH ] value | ENDS [ WITH ] value"""

    def set_op_rhs(self, arg):
        """set_op_rhs: HAS ( [ OPERATOR ] value | ALL value_list | ANY value_list | ONLY value_list )"""

    def length_op_rhs(self, arg):
        """length_op_rhs: LENGTH [ OPERATOR ] value"""

    def set_zip_op_rhs(self, arg):
        """set_zip_op_rhs: property_zip_addon HAS ( value_zip
        | ONLY value_zip_list
        | ALL value_zip_list
        | ANY value_zip_list )

        """

    def property_zip_addon(self, arg):
        """property_zip_addon: ":" property (":" property)*"""

backend_mapping: dict[str, Quantity] property

A mapping between backend field names (aliases) and the corresponding Quantity object.

quantities: dict[str, Quantity] property writable

A mapping from the OPTIMADE field name to the corresponding Quantity objects.

__default__(data, children, meta)

The default rule to call when no definition is found for a particular construct.

Source code in optimade/filtertransformers/base_transformer.py 
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def __default__(self, data, children, meta):
    """The default rule to call when no definition is found for a particular construct."""
    raise NotImplementedError(
        f"Calling __default__, i.e., unknown grammar concept. data: {data}, children: {children}, meta: {meta}"
    )

__init__(mapper=None)

Initialise the transformer object, optionally loading in a resource mapper for use when post-processing.

Source code in optimade/filtertransformers/base_transformer.py 
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def __init__(
    self, mapper: Optional[type[BaseResourceMapper]] = None
):  # pylint: disable=super-init-not-called
    """Initialise the transformer object, optionally loading in a
    resource mapper for use when post-processing.

    """
    self.mapper = mapper

comparison(value)

comparison: constant_first_comparison | property_first_comparison

Source code in optimade/filtertransformers/base_transformer.py 
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@v_args(inline=True)
def comparison(self, value):
    """comparison: constant_first_comparison | property_first_comparison"""
    # Note: Return as is.
    return value

constant(value)

constant: string | number

Source code in optimade/filtertransformers/base_transformer.py 
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@v_args(inline=True)
def constant(self, value):
    """constant: string | number"""
    # Note: Return as is.
    return value

constant_first_comparison(arg)

constant_first_comparison: constant OPERATOR ( non_string_value | not_implemented_string )

Source code in optimade/filtertransformers/base_transformer.py 
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def constant_first_comparison(self, arg):
    """constant_first_comparison: constant OPERATOR ( non_string_value | not_implemented_string )"""

expression(arg)

expression: expression_clause ( OR expression_clause )

Source code in optimade/filtertransformers/base_transformer.py 
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def expression(self, arg):
    """expression: expression_clause ( OR expression_clause )"""

expression_clause(arg)

expression_clause: expression_phrase ( AND expression_phrase )*

Source code in optimade/filtertransformers/base_transformer.py 
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def expression_clause(self, arg):
    """expression_clause: expression_phrase ( AND expression_phrase )*"""

expression_phrase(arg)

expression_phrase: [ NOT ] ( comparison | "(" expression ")" )

Source code in optimade/filtertransformers/base_transformer.py 
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def expression_phrase(self, arg):
    """expression_phrase: [ NOT ] ( comparison | "(" expression ")" )"""

filter(arg)

filter: expression*

Source code in optimade/filtertransformers/base_transformer.py 
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def filter(self, arg):
    """filter: expression*"""
    return arg[0] if arg else None

fuzzy_string_op_rhs(arg)

fuzzy_string_op_rhs: CONTAINS value | STARTS [ WITH ] value | ENDS [ WITH ] value

Source code in optimade/filtertransformers/base_transformer.py 
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def fuzzy_string_op_rhs(self, arg):
    """fuzzy_string_op_rhs: CONTAINS value | STARTS [ WITH ] value | ENDS [ WITH ] value"""

known_op_rhs(arg)

known_op_rhs: IS ( KNOWN | UNKNOWN )

Source code in optimade/filtertransformers/base_transformer.py 
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def known_op_rhs(self, arg):
    """known_op_rhs: IS ( KNOWN | UNKNOWN )"""

length_op_rhs(arg)

length_op_rhs: LENGTH [ OPERATOR ] value

Source code in optimade/filtertransformers/base_transformer.py 
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def length_op_rhs(self, arg):
    """length_op_rhs: LENGTH [ OPERATOR ] value"""

non_string_value(value)

non_string_value: number | property

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@v_args(inline=True)
def non_string_value(self, value):
    """non_string_value: number | property"""
    # Note: Return as is.
    return value

not_implemented_string(value)

not_implemented_string: value

Raises:

Type Description
NotImplementedError

For further information, see Materials-Consortia/OPTIMADE issue 157: https://github.com/Materials-Consortia/OPTIMADE/issues/157
Source code in optimade/filtertransformers/base_transformer.py 
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@v_args(inline=True)
def not_implemented_string(self, value):
    """not_implemented_string: value

    Raises:
        NotImplementedError: For further information, see Materials-Consortia/OPTIMADE issue 157:
            https://github.com/Materials-Consortia/OPTIMADE/issues/157

    """
    raise NotImplementedError("Comparing strings is not yet implemented.")

number(number)

number: SIGNED_INT | SIGNED_FLOAT

Source code in optimade/filtertransformers/base_transformer.py 
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@v_args(inline=True)
def number(self, number):
    """number: SIGNED_INT | SIGNED_FLOAT"""
    if TYPE_CHECKING:  # pragma: no cover
        type_: Union[type[int], type[float]]

    if number.type == "SIGNED_INT":
        type_ = int
    elif number.type == "SIGNED_FLOAT":
        type_ = float
    return type_(number)

postprocess(query)

Post-process the query according to the rules defined for the backend, returning the backend-specific query.

Source code in optimade/filtertransformers/base_transformer.py 
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def postprocess(self, query) -> Any:
    """Post-process the query according to the rules defined for
    the backend, returning the backend-specific query.

    """
    return query

property(args)

property: IDENTIFIER ( "." IDENTIFIER )*

If this transformer has an associated mapper, the property will be compared to possible relationship entry types and for any supported provider prefixes. If there is a match, this rule will return a string and not a dereferenced Quantity.

Raises:

Type Description
BadRequest

If the property does not match any of the above rules.
Source code in optimade/filtertransformers/base_transformer.py 
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def property(self, args: list) -> Any:
    """property: IDENTIFIER ( "." IDENTIFIER )*

    If this transformer has an associated mapper, the property
    will be compared to possible relationship entry types and
    for any supported provider prefixes. If there is a match,
    this rule will return a string and not a dereferenced
    [`Quantity`][optimade.filtertransformers.base_transformer.Quantity].

    Raises:
        BadRequest: If the property does not match any
            of the above rules.

    """
    quantity_name = str(args[0])

    # If the quantity name matches an entry type (indicating a relationship filter)
    # then simply return the quantity name; the inherited property
    # must then handle any further nested identifiers
    if self.mapper:
        if quantity_name in self.mapper.RELATIONSHIP_ENTRY_TYPES:
            return quantity_name

    if self.quantities and quantity_name not in self.quantities:
        # If the quantity is provider-specific, but does not match this provider,
        # then return the quantity name such that it can be treated as unknown.
        # If the prefix does not match another known provider, also emit a warning
        # If the prefix does match a known provider, do not return a warning.
        # Following [Handling unknown property names](https://github.com/Materials-Consortia/OPTIMADE/blob/master/optimade.rst#handling-unknown-property-names)
        if self.mapper and quantity_name.startswith("_"):
            prefix = quantity_name.split("_")[1]
            if prefix not in self.mapper.SUPPORTED_PREFIXES:
                if prefix not in self.mapper.KNOWN_PROVIDER_PREFIXES:
                    warnings.warn(
                        UnknownProviderProperty(
                            f"Field {quantity_name!r} has an unrecognised prefix: this property has been treated as UNKNOWN."
                        )
                    )

                return quantity_name

        raise BadRequest(
            detail=f"'{quantity_name}' is not a known or searchable quantity"
        )

    quantity = self.quantities.get(quantity_name, None)
    if quantity is None:
        quantity = self._quantity_type(name=str(quantity_name))

    return quantity

property_first_comparison(arg)

property_first_comparison: property ( value_op_rhs | known_op_rhs | fuzzy_string_op_rhs | set_op_rhs | set_zip_op_rhs | length_op_rhs )

Source code in optimade/filtertransformers/base_transformer.py 
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def property_first_comparison(self, arg):
    """property_first_comparison:
    property ( value_op_rhs
             | known_op_rhs
             | fuzzy_string_op_rhs
             | set_op_rhs
             | set_zip_op_rhs
             | length_op_rhs )

    """

property_zip_addon(arg)

property_zip_addon: ":" property (":" property)*

Source code in optimade/filtertransformers/base_transformer.py 
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def property_zip_addon(self, arg):
    """property_zip_addon: ":" property (":" property)*"""

set_op_rhs(arg)

set_op_rhs: HAS ( [ OPERATOR ] value | ALL value_list | ANY value_list | ONLY value_list )

Source code in optimade/filtertransformers/base_transformer.py 
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def set_op_rhs(self, arg):
    """set_op_rhs: HAS ( [ OPERATOR ] value | ALL value_list | ANY value_list | ONLY value_list )"""

set_zip_op_rhs(arg)

set_zip_op_rhs: property_zip_addon HAS ( value_zip | ONLY value_zip_list | ALL value_zip_list | ANY value_zip_list )

Source code in optimade/filtertransformers/base_transformer.py 
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def set_zip_op_rhs(self, arg):
    """set_zip_op_rhs: property_zip_addon HAS ( value_zip
    | ONLY value_zip_list
    | ALL value_zip_list
    | ANY value_zip_list )

    """

signed_int(number)

signed_int : SIGNED_INT

Source code in optimade/filtertransformers/base_transformer.py 
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@v_args(inline=True)
def signed_int(self, number):
    """signed_int : SIGNED_INT"""
    return int(number)

string(string)

string: ESCAPED_STRING

Source code in optimade/filtertransformers/base_transformer.py 
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@v_args(inline=True)
def string(self, string):
    """string: ESCAPED_STRING"""
    return string.strip('"')

transform(tree)

Transform the query using the Lark Transformer then run the backend-specific post-processing methods.

Source code in optimade/filtertransformers/base_transformer.py 
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def transform(self, tree: Tree) -> Any:
    """Transform the query using the Lark `Transformer` then run the
    backend-specific post-processing methods.

    """
    return self.postprocess(super().transform(tree))

value(value)

value: string | number | property

Source code in optimade/filtertransformers/base_transformer.py 
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@v_args(inline=True)
def value(self, value):
    """value: string | number | property"""
    # Note: Return as is.
    return value

value_list(arg)

value_list: [ OPERATOR ] value ( "," [ OPERATOR ] value )*

Source code in optimade/filtertransformers/base_transformer.py 
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def value_list(self, arg):
    """value_list: [ OPERATOR ] value ( "," [ OPERATOR ] value )*"""

value_op_rhs(operator, value)

value_op_rhs: OPERATOR value

Source code in optimade/filtertransformers/base_transformer.py 
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@v_args(inline=True)
def value_op_rhs(self, operator, value):
    """value_op_rhs: OPERATOR value"""

value_zip(arg)

value_zip: [ OPERATOR ] value ":" [ OPERATOR ] value (":" [ OPERATOR ] value)*

Source code in optimade/filtertransformers/base_transformer.py 
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def value_zip(self, arg):
    """value_zip: [ OPERATOR ] value ":" [ OPERATOR ] value (":" [ OPERATOR ] value)*"""
    pass

value_zip_list(arg)

value_zip_list: value_zip ( "," value_zip )*

Source code in optimade/filtertransformers/base_transformer.py 
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def value_zip_list(self, arg):
    """value_zip_list: value_zip ( "," value_zip )*"""

Quantity

Class to provide information about available quantities to the transformer.

The transformer can use Quantity's to

  • do some semantic checks,
  • map quantities to the underlying backend field name.

Attributes:

Name Type Description
name str

The name of the quantity as used in the filter expressions.
backend_field Optional[str]

The name of the field for this quantity in the backend database, will be name by default.
length_quantity Optional[Quantity]

Another (typically integer) Quantity that can be queried as the length of this quantity, e.g. elements and nelements. Backends can then decide whether to use this for all "LENGTH" queries.
Source code in optimade/filtertransformers/base_transformer.py 
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class Quantity:
    """Class to provide information about available quantities to the transformer.

    The transformer can use [`Quantity`][optimade.filtertransformers.base_transformer.Quantity]'s to

    * do some semantic checks,
    * map quantities to the underlying backend field name.

    Attributes:
        name: The name of the quantity as used in the filter expressions.
        backend_field: The name of the field for this quantity in the backend database, will be
            `name` by default.
        length_quantity: Another (typically integer) [`Quantity`][optimade.filtertransformers.base_transformer.Quantity]
            that can be queried as the length of this quantity, e.g. `elements` and `nelements`. Backends
            can then decide whether to use this for all "LENGTH" queries.

    """

    name: str
    backend_field: Optional[str]
    length_quantity: Optional["Quantity"]

    def __init__(
        self,
        name: str,
        backend_field: Optional[str] = None,
        length_quantity: Optional["Quantity"] = None,
    ):
        """Initialise the `quantity` from it's name and aliases.

        Parameters:
            name: The name of the quantity as used in the filter expressions.
            backend_field: The name of the field for this quantity in the backend database, will be
                `name` by default.
            length_quantity: Another (typically integer) [`Quantity`][optimade.filtertransformers.base_transformer.Quantity]
                that can be queried as the length of this quantity, e.g. `elements` and `nelements`. Backends
                can then decide whether to use this for all "LENGTH" queries.

        """

        self.name = name
        self.backend_field = backend_field if backend_field is not None else name
        self.length_quantity = length_quantity

__init__(name, backend_field=None, length_quantity=None)

Initialise the quantity from it's name and aliases.

Parameters:

Name Type Description Default
name str

The name of the quantity as used in the filter expressions.

 required
backend_field Optional[str]

The name of the field for this quantity in the backend database, will be name by default.

 None
length_quantity Optional[Quantity]

Another (typically integer) Quantity that can be queried as the length of this quantity, e.g. elements and nelements. Backends can then decide whether to use this for all "LENGTH" queries.

 None
Source code in optimade/filtertransformers/base_transformer.py 
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def __init__(
    self,
    name: str,
    backend_field: Optional[str] = None,
    length_quantity: Optional["Quantity"] = None,
):
    """Initialise the `quantity` from it's name and aliases.

    Parameters:
        name: The name of the quantity as used in the filter expressions.
        backend_field: The name of the field for this quantity in the backend database, will be
            `name` by default.
        length_quantity: Another (typically integer) [`Quantity`][optimade.filtertransformers.base_transformer.Quantity]
            that can be queried as the length of this quantity, e.g. `elements` and `nelements`. Backends
            can then decide whether to use this for all "LENGTH" queries.

    """

    self.name = name
    self.backend_field = backend_field if backend_field is not None else name
    self.length_quantity = length_quantity

UnknownProviderProperty

Bases: OptimadeWarning

A provider-specific property has been requested via response_fields or as in a filter that is not recognised by this implementation.

Source code in optimade/warnings.py 
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class UnknownProviderProperty(OptimadeWarning):
    """A provider-specific property has been requested via `response_fields` or as in a `filter` that is not
    recognised by this implementation.

    """